Wrong result in multiplying in javascript

Question

Possible Duplicate:
Is JavaScript's Math broken?

I have two variables

var first : float = 200;
var next : float;
next = first * 1.2;

and when i write in debug log "next" it gives 40,00002. any advices?

This is not the javascript syntax !!!, this is maybe actionscript or something else — amd, Apr 20 '12 at 09:28
Where did you get the syntax first : float from? JavaScript doesn't define types. like that... — BeRecursive, Apr 20 '12 at 09:28
`40,00002` really? Not `240,00002`? (but even that is strange as demonstrated by Adil in his answer). — Thilo, Apr 20 '12 at 09:32

score 2 · Answer 1 · answered Apr 20 '12 at 09:29

2

The precision of floating point computations is only as precise as the precision (no of bits and mantissa) it uses. http://en.wikipedia.org/wiki/Floating_point#Machine_precision_and_backward_error_analysis

answered Apr 20 '12 at 09:29

clyfe

1

also see http://stackoverflow.com/questions/1458633/elegant-workaround-for-javascript-floating-point-number-problem – clyfe Apr 20 '12 at 09:30

Adil · Answer 2 · 2012-04-20T09:43:42.693

2

This give you 240. I think your are not not following the standard. I even parsed it with float

var first =parseFloat(200.0);
var next ;
next = parseFloat(first * 1.2);
alert(next);

edited Apr 20 '12 at 09:43

answered Apr 20 '12 at 09:29

Adil

2 Answers2